Laminating machines apply a film of transparent flexible plastic material to a print so as to provide a protective surface to the print. On some occasions it is necessary to apply a laminating material to only one surface of a print, but in other circumstances it is desirable to apply a laminating material to both the upper and lower surfaces of a print and encapsulate the printed material between the lamination. In other cases, it is desirable to apply a laminating material to the upper surface of a print and attach the lower surface of a print to a mounting board. It is therefore desirable to provide a laminating machine which can be used to perform all of the above functions.
Print material is available in large rolls of paper, or the like, which may be used, for example, to make a long sign. In such cases it is desirable to apply a lamination to one or both sides of print material which is available on a roll. Present laminating machines require that the print material be sliced into manageable sections and each section fed into a laminating machine for lamination. It would be desirable to provide a laminating machine which could accept an entire roll of print material and feed one end of the roll into the laminating machine and laminate the roll of print material in a continuous operation. It is also desirable to have a laminating machine which retains a second, back-up roll of laminating film which can be fed into the machine with little or no interruption of the operation thereof when the first roll of laminating material is exhausted.
There are two types of laminating material currently available, one of which is pressure sensitive, and the other of which is heat activated. The pressure sensitive laminating material has an adhesive on one side thereof and is applied to print material by using parallel rollers to compress the adhesive side of the laminating material against the print. Pressure sensitive laminating material is more expensive than heat activated laminating material, and pressure sensitive laminating material does not bond directly to the print material. Print material to which a pressure sensitive laminating material has been applied, cannot be easily rolled onto a spool.
Heat activated laminating material, on the other hand, has an adhesive chemical which becomes activated at temperatures of approximately 200.degree. F. Laminator which are adapted to apply heat activated laminating material have a heated roller which maintains a temperature which will activate the adhesive chemicals of the laminating material and apply it to the print material. An operator of the laminating machine may become injured during the course of operation if his hand becomes pinched between the rollers of the machine, and if a heat activated laminated material is being applied, the operator may also suffer burns. It would be desirable, therefore, to provide a laminating machine which can perform a wide variety of functions, and have safety features to release the pressure between the rollers and turn off the heating elements to prevent or minimize injury to an operator.
Currently existing laminating machines have temperature sensing devices which contact the heated roller to determine the temperature of the roller. Such temperature sensing devices may not accurately assess the temperature of the work surface of the roller, and as a result, either too much or too little heat may be applied to the laminating material. Too little heat may fail to activate the adhesive chemicals and as a result the laminating material may not adhere to the surface of the print. Too much heat may result in the destruction of the laminating material before it is applied to the print. It is, therefore, necessary that the temperature of the roller be accurately maintained across the work surface thereof.
Another problem experienced by existing machines is that print material frequently has curled edges, or has irregularities in its surface such that it is difficult to feed the print material into the machine without causing wrinkles which will become laminated into the print. It would be desirable to provide a means for drawing the print material evenly across the feed table of the laminating machine so as to avoid curling, wrinkling or folding.
When a laminating machine is to be used to laminate a lengthy roll of print material, the machine must evenly draw material off an input roll of print without causing wrinkles or imperfections and will remain aligned with the laminating material as it is applied to the print.
It is further desirable to provide a laminating machine which can overcome all the foregoing problems and will apply both pressure sensitive and heat activated laminating material, and yet not be excessively large and heavy. It is the intent of the present invention to overcome the problems encountered with existing laminating machines.